Color image sensor without the color filters

ABSTRACT

In various embodiments, image sensors and methods of making images sensors are disclosed. In an embodiment, an image sensor includes a first pixel region having a pixel electrode, an optically sensitive material of a first thickness, and a counterelectrode. The images sensor also includes a second pixel region comprising a pixel electrode, an optically sensitive material of a second thickness, and a counterelectrode. The first pixel region is configured to detect light in a first spectral band and the second pixel region is configured to detect light in a second spectral band. The first and second spectral bands include an overlapping spectral range. The second spectral band also includes a spectral range that is substantially undetectable by the first pixel region. Other image sensors and methods of making images sensors are also disclosed.

PRIORITY CLAIM

The present application claims the benefit of priority of U.S.Provisional Patent Application Ser. No. 62/029,014, filed Jul. 25, 2014,and entitled “COLOR IMAGE SENSOR WITHOUT THE COLOR FILTERS,” which isincorporated herein by reference in its entirety.

TECHNICAL FIELD

The present application relates generally to the field of optical andelectronic systems and methods, and methods of making and using thedevices and systems.

BACKGROUND

Embodiments of the disclosed subject matter relate to image sensors,and, more particularly, to image sensors that extract color or otherwavelength-related information, including those that do so with the aidof multi-height light-sensing regions.

Conventional image sensors (CIS, CCD, etc.) typically use a color filterarray (CFA) to extract color information to construct color images. Acommon method uses Red (R), Green (G), and Blue (B) color filters.

The color filter materials themselves absorb some photons, resulting inloss of quantum efficiency, and hence a lower signal-to-noise ratio(SNR).

Thick color filter material also results in worse Chief-Ray Angle (CRA),which is important in designing thinner camera modules and incorporatinglarge aperture lenses.

Additionally, CFA process variations, such as thickness, size, andalignment, may cause excess crosstalk, where a portion of light intendedto impinge only a first class of pixel regions associated with a firstintended color in fact is incident on a second class associated with asecond color. Such CFA process variations may also producenon-uniformity issues, further lowering the SNR, resulting in poorimages.

Furthermore, a CFA is often responsible for reliability failures, andobvious process costs associated with the CFA process and yield loss areundesirable.

SUMMARY

Embodiments of the disclosed subject matter describe solutions thatenable color sensing without the use of passive, separate color filters.

Materials have a defined penetration depth for a given wavelength oflight. For example, for silicon, red light penetrates more deeply thandoes blue light. Consequently, one can make a thin piece of silicon thatcan absorb blue light very well, but cannot absorb red light very well.

For example, using this principle, one can design image sensor pixelsthat can be:

-   -   Type 1: Of a first, lower, thickness: Absorbs only blue light        efficiently;    -   Type 2: Of a second, intermediate, thickness: Absorbs blue and        green light efficiently, but red light only inefficiently; and    -   Type 3: Absorbs blue, green, and red light efficiently.

By properly arranging the above types of pixels, including, but notlimited to, a conventional Bayer Pattern, one can extract necessarycolor information for a given pixel using information from nearbypixels.

The application of this principle is not limited to red, green, and bluewavelengths, but other wavelengths can be used, including, for example,infrared.

In addition to primary colors such as red, green, and blue, etc. one canuse any color combinations, including secondary colors such as cyan,yellow, magenta, etc.

This method and the disclosed structures can be used with any photonabsorbing materials, including silicon, GaAs, organic, inorganic, andcomposite films. In embodiments, the light-absorbing material mayinclude semiconductor nanoparticles in a matrix.

There are many possible methods to fabricate the aforementioned pixels,including but not limited to, conventional semiconductor processing suchas spin-coating, deposition, epitaxial growth, and implants.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is an example of a Bayer-pattern layout;

FIG. 1B is a cross-sectional view through Green and Red equivalent of anembodiment of the disclosed subject matter;

FIG. 1C is a cross-sectional view through Blue and Green equivalent ofan embodiment of the disclosed subject matter;

FIG. 2A is an example of a Bayer-pattern layout;

FIG. 2B is a cross-sectional view through Green and Red equivalent of anembodiment of the disclosed subject matter;

FIG. 2C is a cross-section view through Blue and Green equivalent of anembodiment of the disclosed subject matter;

FIGS. 3A through 3G show example embodiments of methods andcross-sectional views of making the devices of, for example, FIGS. 1Athrough 1C; and

FIGS. 4A through 4G show example embodiments of methods andcross-sectional views of making the devices of, for example, FIGS. 2Athrough 2C;

FIG. 5 shows overall structure and areas related to a quantum dot pixelchip, according to an embodiment;

FIG. 6 shows an example of a quantum dot;

FIG. 7 shows a two-row by three-column sub-region within a generallylarger array of top-surface electrodes;

FIG. 8 illustrates a 3T transistor configuration for interfacing withthe quantum dot material;

FIG. 9 is a block diagram of an example system configuration that may beused in combination with embodiments described herein;

FIG. 10 shows an embodiment of a single-plane computing device that maybe used in computing, communication, gaming, interfacing, and so on;

FIG. 11 shows an embodiment of a double-plane computing device that maybe used in computing, communication, gaming, interfacing, and so on;

FIG. 12 shows an embodiment of a camera module that may be used with thecomputing devices of FIG. 10 or FIG. 11;

FIG. 13 shows an embodiment of a light sensor that may be used with thecomputing devices of FIG. 10 or FIG. 11;

FIG. 14 and FIG. 15 show embodiments of methods of gesture recognition;

FIG. 16 shows an embodiment of a three-electrode differential-layoutsystem to reduce external interferences with light sensing operations;

FIG. 17 shows an embodiment of a three-electrode twisted-pair layoutsystem to reduce common-mode noise from external interferences in lightsensing operations;

FIG. 18 is an embodiment of time-modulated biasing a signal applied toelectrodes to reduce external noise that is not at the modulationfrequency;

FIG. 19 shows an embodiment of a transmittance spectrum of a filter thatmay be used in various imaging applications;

FIG. 20 shows an example schematic diagram of a circuit that may beemployed within each pixel to reduce noise power; and

FIG. 21 shows an example schematic diagram of a circuit of aphotoGate/pinned-diode storage that may be implemented in silicon.

Embodiments are described, by way of example only, with reference to theaccompanying drawings. The drawings are not necessarily to scale. Forclarity and conciseness, certain features of the embodiment may beexaggerated and shown in schematic form.

DETAILED DESCRIPTION

FIG. 1A shows an example of a Bayer-pattern layout. FIG. 1B and FIG. 1Care examples of embodiments of the disclosed subject matter, across theBayer pattern row where the Green and Red equivalent pixels are located.

In this embodiment, Green equivalent pixel 10, Red equivalent pixel 20,and Blue equivalent pixel 30 are composed of photon absorbing layers.Photon absorbing layers can comprised be any photon absorbing materialor materials. The photon absorbing material or materials can bedeposited or grown by various methods.

Charge collecting structure 60 can include transfer transistor, metalelectrodes, vias, etc.

A micro-lens (U-LENS or μ-lens) 50 is optional, as it may help improveCRA and X-talk.

There may be other features such as anti-reflective coating, which arenot depicted in the illustration to avoid obscuring other aspects of thedisclosed subject matter.

Using near-by pixels (for example, subtraction), one can extract colorinformation of each pixel.

In more detail, with continuing reference to FIG. 1A through FIG. 1C,the thicknesses of the light absorbing layers 10, 20, 30 are selectedaccording to colors for which they are targeted to absorb. For example,for light that is reaching the Blue equivalent pixel 30, blue photonsare substantially absorbed and longer wavelengths of photons, such asGreen and Red photons, mostly pass through the thin blue light absorbinglayer 30. For light that reaches the Green equivalent pixel 10, blue andgreen photons are substantially absorbed, and the Red photons mostlypass through. Similarly, for light that reaches the Red equivalent pixel20, all three Blue, Green, and Red photons are substantially absorbed.

In further detail, still referring to FIGS. 1A through FIG. 1C, havingthree types of pixels each absorbing blue photons 30, blue+green 10, andblue+green+red 20, one can extract separate blue, green, and red signalsusing neighboring pixel information. The thickness of each lightabsorbing layer 10, 20, 30, is chosen dependent on which wavelengths oflight the layer is targeted to absorb, taken together with the materialproperties such as extinction coefficients, carrier mobility, etc. Inone embodiment, the thickness of the blue absorbing layer 30, may be inthe thickness range of about 0.1 μm to about 0.3 μm, blue+greenabsorbing layer 10 may be in the range of about 0.2 μm to about 0.5 μm,and the red+blue+green absorbing layer 20 may be in the range of about0.4 μm to about 1 μm in thickness. If different wavelengths are used todecipher color information, the thicknesses of the light absorbinglayers may be changed.

Example embodiments of methods of making the devices of FIG. 1A through1C are depicted in FIGS. 3A through FIG. 3G. In these embodiments, usingthree different color absorptions can use three different thicknesses ofthe light absorbing material 36 (FIG. 3G). FIG. 3B and FIG. 3C depictthe formation of a first type of electrode using a conventional back-endof line (BEOL) process. On top of the via 32, an etch stop layer (ESL)34 is deposited and patterned. The ESL 34 can be, but is not limited to,silicon nitride, silicon oxynitride, titanium, titanium nitride,aluminum, etc. This process is repeated to form all three types ofelectrodes as shown in the FIG. 3E. Then, using conventional lithographyand etch processes, and using the etch stop layer 34, an oxide on top ofthe two types of electrodes are removed, resulting in FIG. 3F. On thisready substrate, the light absorbing layer 36 can be deposited, as shownin FIG. 3G.

Referring now to FIG. 2B and FIG. 2C are examples of another embodimentof the disclosed subject matter, across the Bayer pattern row where theGreen and Red equivalent pixels are located.

In this embodiment, the Green equivalent pixel 10, a Red equivalentpixel 220, and a Blue equivalent pixel 230 are composed of photonabsorbing layers. Photon absorbing layers can be comprised of any photonabsorbing material or materials. The photon absorbing layer or layerscan be deposited or grown by various methods.

The charge collecting structure 60 can include transfer transistor,metal electrodes, vias, etc.

A Micro-lens (U-LENS or μ-lens) 250 can help improve CRA and X-talk.

There may be other features such as anti-reflective coating, which arenot depicted in the illustration to avoid obscuring other aspects of thedisclosed subject matter.

Using near-by pixels (for example, subtraction), one can extract colorinformation of each pixel.

Referring to FIG. 2A to FIG. 2C, the thicknesses of the light absorbinglayers 10, 220, 230 are modulated, according to colors which they aretargeted to absorb. For example, for light that is reaching the Blueequivalent pixel 230, blue photons are substantially absorbed and longerwavelengths of photons, such as Green and Red photons, mostly passthrough the thin blue light absorbing layer 230. For light that reachesthe Green equivalent pixel 10, blue and green photons are substantiallyabsorbed, and the Red photons mostly pass through. Similarly, for lightthat reaches the Red equivalent pixel 220, all three Blue, Green, andRed photons are substantially absorbed.

With continuing reference to FIG. 2A through FIG. 2C, there is atransparent and index-engineered layer 280. This layer 280 is used toplanarize the array. Additionally, this layer 280 does not absorb lightand the index is engineered such that it induces internal reflection oflight 300 to help photon collection.

With continuing reference to FIG. 2A to FIG. 2C, having three types ofpixels each absorbing blue photons 230, blue+green 10, andblue+green+red 220, one can extract separate blue, green, and red signalusing neighboring pixel information. The thicknesses of the each of thelight absorbing layers 10, 220, 230, are dependent on which wavelengthsof light they are targeted to absorb, as well as the material propertiessuch as extinction coefficients, carrier mobility, etc.

In one embodiment, the thickness of the blue absorbing layer 230 may bein the thickness range of about 0.1 μm to about 0.3 μm, blue+greenabsorbing layer 10 may be in the range of about 0.2 μm to about 0.5 μm,and the red+blue+green absorbing layer 220 may be in the range of about0.4 μm to about 1 μm in thickness. If different wavelengths are used todecipher color information, the thicknesses of the light absorbinglayers may be changed.

Example embodiments of methods of making the devices of FIG. 2A through2C are depicted in FIG. 4A through FIG. 4G. In these embodiments, usingthree different color absorptions can use three different thicknesses ofthe light absorbing material 44. FIG. 4B depicts the formation of thebottom electrode 42, deposition of the light absorbing layer 44 and thetop electrode 40, which can be, but is not limited to, transparentconductive oxide (TCO), nanoparticles, thick metals, organic and/orinorganic films, etc. Using lithography and etch, the light absorbingmaterial 44 is partially removed, as shown in FIG. 4C. An additional topelectrode 40 is deposited and the lithography and etch process isrepeated to form three different thicknesses of the light absorbinglayer 44, all covered with the top electrode 40, which is shown on theFIG. 4F. To planarize the array, the transparent planarizing layer 46 isapplied, as shown in FIG. 4G.

The various illustrations of the methods and apparatuses provided hereinare intended to provide a general understanding of the structure ofvarious embodiments and are not intended to provide a completedescription of all the elements and features of the apparatuses andmethods that might make use of the structures, features, and materialsdescribed herein.

As discussed herein, in conventional images sensors, such as CMOS imagesensors, typically used is a color filter array (CFA) to extract colorinformation to construct color images. One common method uses Red,Green, and Blue (RGB) color filters; another uses Cyan, Green, Yellow,Magenta (CYGM); another uses Red, Green, Blue, and White (RGBW)implementation.

The disclosed subject matter, in embodiments, eliminates the need for aCFA. In alternative embodiments, the disclosed subject matter removesthe need for at least one filter type (e.g., RGB solution can beimplemented without at least one of an R, G, or B passive filter).

A current challenge with the use of CFA relates to successfully scalingconventional image sensors. Patterning small features such as regions ofCFA to less than 1 μm is challenging. Doing so can negatively impactfilter shape, spectral properties, crosstalk, and manufacturability.

Approaches embodied and discussed herein that eliminate or reduce CFAcan enable scaling to smaller dimensions and with fewer compromises inperformance.

Implementations of CFA that rely on a thick filter, typically in therange of about 0.4 μm to about 1.0 μm, typically suffer in their angularresponse as a result of the high vertical height combined with smalllateral dimensions. Rays entering the color filter at a highlyoff-normal-incidence angle may be conveyed, not to the pixel thatresides beneath the location of impingement, but instead beneath anadjacent pixel. This condition leads to crosstalk.

Embodiments of the disclosed subject matter eliminate at least one CFAlayer, and improve crosstalk by ensuring that spectral filtering isimplemented within the light-absorbing photodetector material itself

Embodiments of the disclosed subject matter thereby enable a higherchief ray angle. This in turn enables design of an optical system thatis lower in height (known as z-height) for a given sensor lateraldimension.

Another disadvantage of typical CFA-based color imaging can reside in anundesired absorption of light within the intended passband. In cases,loss can reach 30% in transmission even within the passband. Eliminatingat least one CFA layer eliminates this source of loss. This can enhancesignal-to-noise ratio at low light (dark-noise-limited regime), and alsoat medium and high light (photon-shot-noise-limited).

The CFA can be a source of failures in reliability of a typical imagesensor. Reasons for the sources of failure include the fact that the CFAcan be exposed to the environment, such as air, ultraviolet light, etc.In cases, protective layers are applied atop a CFA as a result. Byremoving at least one CFA layer or material as described herein, yieldloss may be reduced. By removing at least one CFA layer, reliability maybe improved. By removing at least one CFA layer, the extent ofprotective coatings required may be reduced or eliminated.

Embodiments of the disclosed subject matter include an RGBimplementation. Embodiments also include infrared (IR) wavelengthsensing solutions. In an example embodiment, an RGB-IR pixel matrix isimplemented. One pixel class is made much deeper to also collect IRphotons. IR sensing capability can thereby be incorporated into avisible sensor.

In embodiments, a pixel class may absorb all of Red, Green, and Blue(e.g., pixel 20 of FIG. 1B). This pixel may be termed a “white pixel.”This pixel can achieve very high signal and consequently highsignal-to-noise ratio for a given level of illumination.

As seen and described with reference to FIGS. 2B and 2C, above,lithography and etching may be used to modulate the thickness of thelight-absorbing layers making up the optically sensitive material.Initially, the photon absorbing layers begin with having a substantiallysingle, or common, thickness throughout. Photolithography is used todefine the B+G pixels 220 and etched to a desired thickness. One exampleprocess is described herein with reference to FIG. 4A through FIG. 4G.An analogous procedure is repeated to define B pixels 230, and thisexample results in three types of pixels RGB. The sensor surface thencan be planarized using a transparent material 280. Depending on theoptical properties of the photon absorbing layers, it is possible toengineer the transparent material 280 to be engineered favorably topromote internal reflection 300 to improve photon collection. Theplanarization layer 230 may be deposited using various methods,including spin coating.

Referring again to FIG. 3A through FIG. 3G, the devices of FIG. 1Athrough FIG. 1C may be fabricated as depicted in FIGS. 3A through FIG.3G. In these embodiments, using three different color absorptions canuse three different thicknesses of the light absorbing material 36. FIG.3B and FIG. 3C show the formation of a first type of electrode using aconventional back-end of line (BEOL) process. On top of the via, an etchstop layer (ESL) 34 is deposited and patterned. The ESL 34 can be, butis not limited to, silicon nitride, silicon oxynitride, titanium,titanium nitride, aluminum, etc. The ESL layer may also be composed ofmultiple layers and not limited to a single material. The ESL will alsodouble as the bottom electrode. Another inter-layer dielectric (ILD),such as oxide, is then deposited and planarized, as shown in the FIG.3C. The thicknesses of the ILD layers are chosen based on the targetthicknesses of the photon absorbing layers. Then the above-describedprocess is repeated until a desired number of layers is reached, and inthis example, three layers, RGB are shown in FIG. 3E. Then, usingconventional anisotropic etch processes such as a reactive ion etch(RIE), and using the etch stop layer 34, an oxide on top of the twotypes of electrodes are removed, resulting in FIG. 3F. The ILD etch isself-stopping on the etch stop layers 34, as well as self-aligned withthe etch stop layers 34. The deposit photon absorption layer 36 is thenformed, as shown in FIG. 3G.

Algorithms and methods may be developed to subtract raw data from pixelsof one class to infer color-specific information related to pixels ofanother class. In an example, raw data are obtained for pixel {B}, andseparately in an adjacent thicker pixel for {B+G}. The computation {B+G}minus {B} allows estimation of {G}, that is, the green spectralcomponent in this pixel region.

Embodiments include using a reduced, but not necessarily zero, number ofCFA types or layers. For example, utilization of a single color filteron one type of pixel can reduce the number of photon absorbing layerthicknesses by one. For example, in the RGB case shown on the FIG. 3F,only two steps instead of three are used, if a color filter is used onone of them. This variation may be beneficial on certain applications asit may simplify image processing, with a possible trade off with thesensitivity.

In one embodiment, an image sensor includes a first pixel regioncomprising a pixel electrode, an optically sensitive material of a firstthickness, and a counterelectrode; a second pixel region comprising apixel electrode, an optically sensitive material of a second thickness,and a counterelectrode; the first pixel region is configured to detectlight in a first spectral band; the second pixel region is configured todetect light in a second spectral band; and the first and secondspectral bands include an overlapping spectral range, the secondspectral band also includes a spectral range that is substantiallyundetectable by the first pixel region.

In various ones of the embodiments discussed herein, additionalembodiments include the optically sensitive layer of the image sensorcomprising at least one semiconductor nanoparticle. In embodiments, thefirst spectral band of the image sensor includes the range of about 450nm to about 490 nm and the second spectral band includes the range ofabout 450 nm to about 570 nm. In embodiments, the first spectral band ofthe image sensor includes the range of about 450 nm to about 490 nm andthe second spectral band includes the range of about 450 nm to about 570nm. In embodiments, the first spectral band of the image sensor includesthe range of about 450 nm to about 570 nm and the second spectral bandincludes the range of about 450 nm to about 630 nm. In embodiments, thefirst spectral band of the image sensor includes the range of about 450nm to about 630 nm and the second spectral band includes the range ofabout 450 nm to about 960 nm. In embodiments, the first spectral band ofthe image sensor includes the range of about 450 nm to about 960 nm andthe second spectral band includes the range of about 450 nm to about1600 nm.

In one embodiment a method of making an image sensor includes producingan integrated circuit having trenches of a first depth defining a firstclass of pixel regions; and trenches of a second depth defining a secondclass of pixel regions; overcoating the trenched integrated circuit witha substantially planarizing optically sensitive material such that adifference in the thickness of the optically sensitive material indifferent regions overlying the integrated circuit is substantiallydefined by a difference in the first and the second trench depths.

In various ones of the embodiments discussed herein, additionalembodiments include the optically sensitive layer employed by the methodcomprising at least one semiconductor nanoparticle.

Referring now to FIG. 5, example embodiments provide image sensingregions that use an array of pixel elements to detect an image. Thepixel elements may include photosensitive material. The image sensor maydetect a signal from the photosensitive material in each of the pixelregions that varies based on the intensity of light incident on thephotosensitive material. In one example embodiment, the photosensitivematerial is a continuous film of interconnected nanoparticles.Electrodes are used to apply a bias across each pixel area. Pixelcircuitry is used to integrate a signal in a charge store over a periodof time for each pixel region. The circuit stores an electrical signalproportional to the intensity of light incident on the opticallysensitive layer during the integration period. The electrical signal canthen be read from the pixel circuitry and processed to construct adigital image corresponding to the light incident on the array of pixelelements. In example embodiments, the pixel circuitry may be formed onan integrated circuit device below the photosensitive material. Forexample, a nanocrystal photosensitive material may be layered over aCMOS integrated circuit device to form an image sensor. Metal contactlayers from the CMOS integrated circuit may be electrically connected tothe electrodes that provide a bias across the pixel regions. U.S. patentapplication Ser. No. 12/10625, titled “Materials, Systems and Methodsfor Optoelectronic Devices,” filed Apr. 18, 2008 (Publication No.20090152664) includes additional descriptions of optoelectronic devices,systems and materials that may be used in connection with exampleembodiments and is hereby incorporated herein by reference in itsentirety. This is an example embodiment only and other embodiments mayuse different photodetectors and photosensitive materials. For example,embodiments may use silicon or Gallium Arsenide (GaAs) photodetectors.

Image sensors incorporate arrays of photodetectors. These photodetectorssense light, converting it from an optical to an electronic signal. FIG.5 shows structure of and areas relating to quantum dot pixel chipstructures (QDPCs) 100, according to example embodiments. As illustratedin FIG. 5, the QDPC 100 may be adapted as a radiation 1000 receiverwhere quantum dot structures 1100 are presented to receive the radiation1000, such as light. The QDPC 100 includes, as will be described in moredetail herein, quantum dot pixels 1800 and a chip 2000 where the chip isadapted to process electrical signals received from the quantum dotpixel 1800. The quantum dot pixel 1800 includes the quantum dotstructures 1100 include several components and sub components such asquantum dots 1200, quantum dot materials 200 and particularconfigurations or quantum dot layouts 300 related to the dots 1200 andmaterials 200. The quantum dot structures 1100 may be used to createphotodetector structures 1400 where the quantum dot structures areassociated with electrical interconnections 1404. The electricalconnections 1404 are provided to receive electric signals from thequantum dot structures and communicate the electric signals on to pixelcircuitry 1700 associated with pixel structures 1500. Just as thequantum dot structures 1100 may be laid out in various patterns, bothplanar and vertical, the photodetector structures 1400 may haveparticular photodetector geometric layouts 1402. The photodetectorstructures 1400 may be associated with pixel structures 1500 where theelectrical interconnections 1404 of the photodetector structures areelectrically associated with pixel circuitry 1700. The pixel structures1500 may also be laid out in pixel layouts 1600 including vertical andplanar layouts on a chip 2000 and the pixel circuitry 1700 may beassociated with other components 1900, including memory for example. Thepixel circuitry 1700 may include passive and active components forprocessing of signals at the pixel 1800 level. The pixel 1800 isassociated both mechanically and electrically with the chip 2000. Inexample embodiments, the pixel structures 1500 and pixel circuitry 1700include structures and circuitry for film binning and/or circuit binningof separate color elements for multiple pixels as described herein. Froman electrical viewpoint, the pixel circuitry 1700 may be incommunication with other electronics (e.g., chip processor 2008). Theother electronics may be adapted to process digital signals, analogsignals, mixed signals and the like and it may be adapted to process andmanipulate the signals received from the pixel circuitry 1700. In otherembodiments, a chip processor 2008 or other electronics may be includedon the same semiconductor substrate as the QDPCs and may be structuredusing a system-on-chip architecture. The other electronics may includecircuitry or software to provide digital binning in example embodiments.The chip 2000 also includes physical structures 2002 and otherfunctional components 2004, which will also be described in more detailbelow.

The QDPC 100 detects electromagnetic radiation 1000, which inembodiments may be any frequency of radiation from the electromagneticspectrum. Although the electromagnetic spectrum is continuous, it iscommon to refer to ranges of frequencies as bands within the entireelectromagnetic spectrum, such as the radio band, microwave band,infrared band (IR), visible band (VIS), ultraviolet band (UV), X-rays,gamma rays, and the like. The QDPC 100 may be capable of sensing anyfrequency within the entire electromagnetic spectrum; however,embodiments herein may reference certain bands or combinations of bandswithin the electromagnetic spectrum. It should be understood that theuse of these bands in discussion is not meant to limit the range offrequencies that the QDPC 100 may sense, and are only used as examples.Additionally, some bands have common usage sub-bands, such as nearinfrared (NIR) and far infrared (FIR), and the use of the broader bandterm, such as IR, is not meant to limit the QDPCs 100 sensitivity to anyband or sub-band. Additionally, in the following description, terms suchas “electromagnetic radiation,” “radiation,” “electromagnetic spectrum,”“spectrum,” “radiation spectrum,” and the like are used interchangeably,and the term color is used to depict a select band of radiation 1000that could be within any portion of the radiation 1000 spectrum, and isnot meant to be limited to any specific range of radiation 1000 such asin visible ‘color’.

In the example embodiment of FIG. 5, the nanocrystal materials andphotodetector structures described above may be used to provide quantumdot pixels 1800 for a photosensor array, image sensor or otheroptoelectronic device. In example embodiments, the pixels 1800 includequantum dot structures 1100 capable of receiving radiation 1000,photodetectors structures adapted to receive energy from the quantum dotstructures 1100 and pixel structures. The quantum dot pixels describedherein can be used to provide the following in some embodiments: highfill factor, color binning, potential to stack, potential to go to smallpixel sizes, high performance from larger pixel sizes, simplify colorfilter array, elimination of de-mosaicing, self-gain setting/automaticgain control, high dynamic range, global shutter capability,auto-exposure, local contrast, speed of readout, low noise readout atpixel level, ability to use larger process geometries (lower cost),ability to use generic fabrication processes, use digital fabricationprocesses to build analog circuits, adding other functions below thepixel such as memory, A to D, true correlated double sampling, binning,etc. Example embodiments may provide some or all of these features.However, some embodiments may not use these features.

A quantum dot 1200 may be a nanostructure, typically a semiconductornanostructure that confines a conduction band electrons, valence bandholes, or excitons (bound pairs of conduction band electrons and valenceband holes) in all three spatial directions. A quantum dot exhibits inits absorption spectrum the effects of the discrete quantized energyspectrum of an idealized zero-dimensional system. The wave functionsthat correspond to this discrete energy spectrum are typicallysubstantially spatially localized within the quantum dot, but extendover many periods of the crystal lattice of the material.

FIG. 6 shows an example of a quantum dot 1200. In one exampleembodiment, the QD 1200 has a core 1220 of a semiconductor or compoundsemiconductor material, such as PbS. Ligands 1225 may be attached tosome or all of the outer surface or may be removed in some embodimentsas described further below. In some embodiments, the cores 1220 ofadjacent QDs may be fused together to form a continuous film ofnanocrystal material with nanoscale features. In other embodiments,cores may be connected to one another by linker molecules.

Some embodiments of the QD optical devices are single image sensor chipsthat have a plurality of pixels, each of which includes a QD layer thatis radiation 1000 sensitive, e.g., optically active, and at least twoelectrodes in electrical communication with the QD layer. The currentand/or voltage between the electrodes is related to the amount ofradiation 1000 received by the QD layer. Specifically, photons absorbedby the QD layer generate electron-hole pairs, such that, if anelectrical bias is applied, a current flows. By determining the currentand/or voltage for each pixel, the image across the chip can bereconstructed. The image sensor chips have a high sensitivity, which canbe beneficial in low-radiation-detecting 1000 applications; a widedynamic range allowing for excellent image detail; and a small pixelsize. The responsivity of the sensor chips to different opticalwavelengths is also tunable by changing the size of the QDs in thedevice, by taking advantage of the quantum size effects in QDs. Thepixels can be made as small as 1 square micron or less, or as large as30 microns by 30 microns or more or any range subsumed therein.

The photodetector structure 1400 of FIGS. 5 and 7 show a deviceconfigured so that it can be used to detect radiation 1000 in exampleembodiments. The detector may be ‘tuned’ to detect prescribedwavelengths of radiation 1000 through the types of quantum dotstructures 1100 that are used in the photodetector structure 1400. Thephotodetector structure can be described as a quantum dot structure 1100with an I/O for some input/output ability imposed to access the quantumdot structures' 1100 state. Once the state can be read, the state can becommunicated to pixel circuitry 1700 through an electricalinterconnection 1404, wherein the pixel circuitry may includeelectronics (e.g., passive and/or active) to read the state. In anembodiment, the photodetector structure 1400 may be a quantum dotstructure 1100 (e.g., film) plus electrical contact pads so the pads canbe associated with electronics to read the state of the associatedquantum dot structure.

In embodiments, processing may include binning of pixels in order toreduce random noise associated with inherent properties of the quantumdot structure 1100 or with readout processes. Binning may involve thecombining of pixels 1800, such as creating 2×2, 3×3, 5×5, or the likesuperpixels. There may be a reduction of noise associated with combiningpixels 1800, or binning, because the random noise increases by thesquare root as area increases linearly, thus decreasing the noise orincreasing the effective sensitivity. With the QDPC's 100 potential forvery small pixels, binning may be utilized without the need to sacrificespatial resolution, that is, the pixels may be so small to begin withthat combining pixels doesn't decrease the required spatial resolutionof the system. Binning may also be effective in increasing the speedwith which the detector can be run, thus improving some feature of thesystem, such as focus or exposure. In example embodiments, binning maybe used to combine subpixel elements for the same color or range ofradiation (including UV and/or IR) to provide separate elements for asuperpixel while preserving color/UV/IR resolution as further describedbelow.

In embodiments the chip may have functional components that enablehigh-speed readout capabilities, which may facilitate the readout oflarge arrays, such as 5 Mpixels, 6 Mpixels, 8 Mpixels, 12 Mpixels, orthe like. Faster readout capabilities may require more complex, largertransistor-count circuitry under the pixel 1800 array, increased numberof layers, increased number of electrical interconnects, widerinterconnection traces, and the like.

In embodiments, it may be desirable to scale down the image sensor sizein order to lower total chip cost, which may be proportional to chiparea. However, shrinking chip size may mean, for a given number ofpixels, smaller pixels. In existing approaches, since radiation 1000must propagate through the interconnect layer onto the monolithicallyintegrated silicon photodiode lying beneath, there is a fill-factorcompromise, whereby part of the underlying silicon area is obscured byinterconnect; and, similarly, part of the silicon area is consumed bytransistors used in read-out. One workaround is micro-lenses, which addcost and lead to a dependence in photodiode illumination on positionwithin the chip (center vs. edges); another workaround is to go tosmaller process geometries, which is costly and particularly challengingwithin the image sensor process with its custom implants.

In embodiments, the technology discussed herein may provide a way aroundthese compromises. Pixel size, and thus chip size, may be scaled downwithout decreasing fill factor. Larger process geometries may be usedbecause transistor size, and interconnect line-width, may not obscurepixels since the photodetectors are on the top surface, residing abovethe interconnect. In the technology proposed herein, large geometriessuch as 0.13 μm and 0.18 μm may be employed without obscuring pixels.Similarly, small geometries such as 90 nm and below may also beemployed, and these may be standard, rather thanimage-sensor-customized, processes, leading to lower cost. The use ofsmall geometries may be more compatible with high-speed digital signalprocessing on the same chip. This may lead to faster, cheaper, and/orhigher-quality image sensor processing on chip. Also, the use of moreadvanced geometries for digital signal processing may contribute tolower power consumption for a given degree of image sensor processingfunctionality.

An example integrated circuit system that can be used in combinationwith the above photodetectors, pixel regions and pixel circuits will nowbe described in connection with FIG. 9. FIG. 9 is a block diagram of animage sensor integrated circuit (also referred to as an image sensorchip). The chip is shown to include:

-   -   i. a pixel array (100) in which incident light is converted into        electronic signals, and in which electronic signals are        integrated into charge stores whose contents and voltage levels        are related to the integrated light incident over the frame        period; the pixel array may include color filters and electrode        structures for color film binning as described further below;    -   ii. row and column circuits (110 and 120) which are used to        reset each pixel, and read the signal related to the contents of        each charge store, in order to convey the information related to        the integrated light over each pixel over the frame period to        the outer periphery of the chip; the pixel circuitry may include        circuitry for color binning as described further below;    -   iii. analog circuits (130, 140, 150, 160, 230). The pixel        electrical signal from the column circuits is fed into the        analog-to-digital convert (160) where it is converted into a        digital number representing the light level at each pixel. The        pixel array and ADC are supported by analog circuits that        provide bias and reference levels (130, 140, & 150).    -   iv. digital circuits (170, 180, 190, 200). The Image Enhancement        circuitry (170) provides image enhancement functions to the data        output from ADC to improve the signal to noise ratio. Line        buffer (180) temporarily stores several lines of the pixel        values to facilitate digital image processing and IO        functionality. (190) is a bank of registers that prescribe the        global operation of the system and/or the frame format. Block        200 controls the operation of the chip. The digital circuits may        also include circuits or software for digital color binning;    -   v. IO circuits (210 & 220) support both parallel input/output        and serial input/output. (210) is a parallel IO interface that        outputs every bit of a pixel value simultaneously. (220) is a        serial IO interface where every bit of a pixel value is output        sequentially; and    -   vi. a phase-locked loop (230) provides a clock to the whole        chip.

In a particular example embodiment, when 0.11 μm CMOS technology node isemployed, the periodic repeat distance of pixels along the row-axis andalong the column-axis may be 900 nm, 1.1 μm, 1.2 μm, 1.4 μm, 1.75 μm,2.2 μm, or larger. The implementation of the smallest of these pixelssizes, especially 900 nm, 1.1 μm, and 1.2 μm, may require transistorsharing among pairs or larger group of adjacent pixels in someembodiments.

Very small pixels can be implemented in part because all of the siliconcircuit area associated with each pixel can be used for read-outelectronics since the optical sensing function is achieved separately,in another vertical level, by the optically-sensitive layer that residesabove the interconnect layer.

Because the optically sensitive layer and the read-out circuit thatreads a particular region of optically sensitive material exist onseparate planes in the integrated circuit, the shape (viewed from thetop) of (1) the pixel read-out circuit and (2) the optically sensitiveregion that is read by (1); can be generally different. For example itmay be desired to define an optically sensitive region corresponding toa pixel as a square; whereas the corresponding read-out circuit may bemost efficiently configured as a rectangle.

In an imaging array based on a top optically sensitive layer connectedthrough vias to the read-out circuit beneath, there exists no imperativefor the various layers of metal, vias, and interconnect dielectric to besubstantially or even partially optically transparent, although they maybe transparent in some embodiments. This contrasts with the case offront-side-illuminated CMOS image sensors in which a substantiallytransparent optical path must exist traversing the interconnect stack.

Pixel circuitry may be defined to include components beginning at theelectrodes in contact with the quantum dot material 200 and ending whensignals or information is transferred from the pixel to other processingfacilities, such as the functional components 2004 of the underlyingchip 200 or another quantum dot pixel 1800. Beginning at the electrodeson the quantum dot material 200, the signal is translated or read. Inembodiments, the quantum dot material 200 may provide a change incurrent flow in response to radiation 1000. The quantum dot pixel 1800may require bias circuitry 1700 in order to produce a readable signal.This signal in turn may then be amplified and selected for readout.

One embodiment of a pixel circuit shown in FIG. 8 uses a reset-biastransistor 1802, amplifier transistor 1804, and column addresstransistor 1808. This three-transistor circuit configuration may also bereferred to as a 3T circuit. Here, the reset-bias transistor 1802connects the bias voltage 1702 to the photoconductive photovoltaicquantum dot material 200 when reset 1704 is asserted, thus resetting theelectrical state of the quantum dot material 200. After reset 1704, thequantum dot material 200 may be exposed to radiation 1000, resulting ina change in the electrical state of the quantum dot material 200, inthis instance a change in voltage leading into the gate of the amplifier1804. This voltage is then boosted by the amplifier transistor 1804 andpresented to the address selection transistor 1808, which then appearsat the column output of the address selection transistor 1808 whenselected. In some embodiments, additional circuitry may be added to thepixel circuit to help subtract out dark signal contributions. In otherembodiments, adjustments for dark signal can be made after the signal isread out of the pixel circuit. In example, embodiments, additionalcircuitry may be added for film binning or circuit binning.

FIG. 10 shows an embodiment of a single-plane computing device 100 thatmay be used in computing, communication, gaming, interfacing, and so on.The single-plane computing device 100 is shown to include a peripheralregion 101 and a display region 103. A touch-based interface device 117,such as a button or touchpad, may be used in interacting with thesingle-plane computing device 100.

An example of a first camera module 113 is shown to be situated withinthe peripheral region 101 of the single-plane computing device 100 andis described in further detail, below. Example light sensors 115A, 115Bare also shown to be situated within the peripheral region 101 of thesingle-plane computing device 100 and are described in further detail,below, with reference to FIG. 13. An example of a second camera module105 is shown to be situated in the display region 103 of thesingle-plane computing device 100 and is described in further detail,below, with reference to FIG. 12.

Examples of light sensors 107A, 107B, shown to be situated in thedisplay region 103 of the single-plane computing device 100 and aredescribed in further detail, below, with reference to FIG. 13. Anexample of a first source of optical illumination 111 (which may bestructured or unstructured) is shown to be situated within theperipheral region 101 of the single-plane computing device 100. Anexample of a second source of optical illumination 109 is shown to besituated in the display region 103.

In embodiments, the display region 103 may be a touchscreen display. Inembodiments, the single-plane computing device 100 may be a tabletcomputer. In embodiments, the single-plane computing device 100 may be amobile handset.

FIG. 11 shows an embodiment of a double-plane computing device 200 thatmay be used in computing, communication, gaming, interfacing, and so on.The double-plane computing device 200 is shown to include a firstperipheral region 201A and a first display region 203A of a first plane210, a second peripheral region 201B and a second display region 203B ofa second plane 230, a first touch-based interface device 217A of thefirst plane 210 and a second touch-based interface device 217B of thesecond plane 230. The example touch-based interface devices 217A, 217Bmay be buttons or touchpads that may be used in interacting with thedouble-plane computing device 200. The second display region 203B mayalso be an input region in various embodiments.

The double-plane computing device 200 is also shown to include examplesof a first camera module 213A in the first peripheral region 201A and asecond camera module 213B in the second peripheral region 201B. Thecamera modules 213A, 213B are described in more detail, below, withreference to FIG. 12. As shown, the camera modules 213A, 213B aresituated within the peripheral regions 201A, 201B of the double-planecomputing device 200. Although a total of two camera modules are shown,a person of ordinary skill in the art will recognize that more or fewerlight sensors may be employed.

A number of examples of light sensors 215A, 215B, 215C, 215D, are shownsituated within the peripheral regions 201A, 201B of the double-planecomputing device 200. Although a total of four light sensors are shown,a person of ordinary skill in the art will recognize that more or fewerlight sensors may be employed. Examples of the light sensors 215A, 215B,215C, 215D, are described, below, in further detail with reference toFIG. 12. As shown, the light sensors 215A, 215B, 215C, 215D, aresituated within the peripheral regions 201A, 201B of the double-planecomputing device 200.

The double-plane computing device 200 is also shown to include examplesof a first camera module 205A in the first display region 203A and asecond camera module 205B in the second display region 203B. The cameramodules 205A, 205B are described in more detail, below, with referenceto FIG. 12. As shown, the camera modules 205A, 205B are situated withinthe display regions 203A, 203B of the double-plane computing device 200.Also shown as being situated within the display regions 203A, 203B ofthe double-plane computing device 200 are examples of light sensors207A, 207B, 207C, 207D. Although a total of four light sensors areshown, a person of ordinary skill in the art will recognize that more orfewer light sensors may be employed. Examples of the light sensors 207A,207B, 207C, 207D are described, below, in further detail with referenceto FIG. 13. Example sources of optical illumination 211A, 211B are shownsituated within the peripheral region 201A, 201B and other examplesources of optical illumination 209A, 209B are shown situated within oneof the display regions 203A, 203B and are also described with referenceto FIG. 13, below. A person of ordinary skill in the art will recognizethat various numbers and locations of the described elements, other thanthose shown or described, may be implemented.

In embodiments, the double-plane computing device 200 may be a laptopcomputer. In embodiments, the double-plane computing device 200 may be amobile handset.

With reference now to FIG. 12, an embodiment of a camera module 300 thatmay be used with the computing devices of FIG. 10 or FIG. 11 is shown.The camera module 300 may correspond to the camera module 113 of FIG. 10or the camera modules 213A, 213B of FIG. 11. As shown in FIG. 12, thecamera module 300 includes a substrate 301, an image sensor 303, andbond wires 305. A holder 307 is positioned above the substrate. Anoptical filter 309 is shown mounted to a portion of the holder 307. Abarrel 311 holds a lens 313 or a system of lenses.

FIG. 13 shows an embodiment of a light sensor 400 that may be used withthe computing devices of FIG. 10 or FIG. 11 an example embodiment of alight sensor. The light sensor 400 may correspond to the light sensors115A, 115B of FIG. 10 of the light sensors 215A, 215B, 215C, 215D ofFIG. 11. The light sensor 400 is shown to include a substrate 401, whichmay correspond to a portion of either or both of the peripheral region101 or the display region 103 of FIG. 10. The substrate 401 may alsocorrespond to a portion of either or both of the peripheral regions201A, 201B or the display regions 203A, 203B of FIG. 11. The lightsensor 400 is also shown to include electrodes 403A, 403B used toprovide a bias across light-absorbing material 405 and to collectphotoelectrons therefrom. An encapsulation material 407 or a stack ofencapsulation materials is shown over the light-absorbing material 405.Optionally, the encapsulation material 407 may include conductiveencapsulation material for biasing and/or collecting photoelectrons fromthe light-absorbing material 405.

Elements of a either the single-plane computing device 100 of FIG. 10,or the double-plane computing device 200 of FIG. 11, may be connected orotherwise coupled with one another. Embodiments of the computing devicesmay include a processor. It may include functional blocks, and/orphysically distinct components, that achieve computing, imageprocessing, digital signal processing, storage of data, communication ofdata (through wired or wireless connections), the provision of power todevices, and control of devices. Devices that are in communication withthe processor include devices of FIG. 10 may include the display region103, the touch-based interface device 117, the camera modules 105, 113,the light sensors 115A, 115B, 107A, 107B, and the sources of opticalillumination 109, 111. Similarly correspondences may apply to FIG. 11 aswell.

The light sensor of FIG. 13 may include a light-absorbing material 405of various designs and compositions. In embodiments, the light-absorbingmaterial may be designed to have an absorbance that is sufficientlysmall, across the visible wavelength region approximately 450 nm to 650nm, such that, in cases in which the light sensor of FIG. 13 isincorporated into the display region of a computing device, only amodest fraction of visible light incident upon the sensor is absorbed bythe light-absorbing material. In this case, the quality of the imagesdisplayed using the display region is not substantially compromised bythe incorporation of the light-absorbing material along the optical pathof the display. In embodiments, the light-absorbing material 405 mayabsorb less than 30%, or less than 20%, or less than 10%, of lightimpinging upon it in across the visible spectral region.

In embodiments, the electrodes 403A, 403B, and, in the case of aconductive encapsulant for 407, the top electrode 407, may beconstituted using materials that are substantially transparent acrossthe visible wavelength region approximately 450 nm to 650 nm. In thiscase, the quality of the images displayed using the display region isnot substantially compromised by the incorporation of thelight-absorbing material along the optical path of the display.

In embodiments, the light sensor of FIG. 13 may include a light-sensingmaterial capable of sensing infrared light. In embodiments, thelight-sensing material may be a semiconductor having a bandgapcorresponding to an infrared energy, such as in the range 0.5 eV-1.9 eV.In embodiments, the light-sensing material may have measurableabsorption in the infrared spectral range; and may have measurableabsorption also in the visible range. In embodiments, the light-sensingmaterial may absorb a higher absorbance in the visible spectral range asin the infrared spectral range; yet may nevertheless be used to sensegesture-related signals in the infrared spectral range.

In an example embodiment, the absorbance of the light-sensingdisplay-incorporated material may lie in the range 2-20% in the visible;and may lie in the range 0.1-5% in the infrared. In an exampleembodiment, the presence of visible light in the ambient, and/or emittedfrom the display, may produce a background signal within the lightsensor, as a consequence of the material visible-wavelength absorptionwithin the light-absorbing material of the light sensor. In an exampleembodiment, sensing in the infrared region may also be achieved. Thelight sources used in aid of gesture recognition may be modulated usingspatial, or temporal, codes, allowing them to be distinguished from thevisible-wavelength-related component of the signal observed in the lightsensor. In an example embodiment, at least one light source used in aidof gesture recognition may be modulated in time using a code having afrequency component greater than 100 Hz, 1000 Hz, 10 kHz, or 100 kHz. Inan example embodiment, the light sensor may have a temporal responsehaving a cutoff frequency greater than said frequency components. Inembodiments, circuitry may be employed to ensure that the frequencycomponent corresponding to gesture recognition can be extracted andmonitored, with the background components related to the room ambient,the display illumination, and other such non-gesture-related backgroundinformation substantially removed. In this example, the light sensors,even though they absorb both visible and infrared light, can provide asignal that is primarily related to gestural information of interest ingesture recognition.

In an example embodiment, an optical source having a total optical powerof approximately 1 mW may be employed. When illuminating an object adistance approximately 10 cm away, where the object has areaapproximately 1 cm² and diffuse reflectance approximately 20%, then theamount of power incident on a light sensor having area 1 cm2 may be oforder 100 pW. In an example embodiment, a light sensor having absorbanceof 1% may be employed, corresponding to a photocurrent related to thelight received as a consequence of the illumination via the opticalsource, and reflected or scattered off of the object, and thus incidentonto the light sensor, may therefore be of order pW. In exampleembodiments, the electrical signal reported by the light sensor maycorrespond to approximately pA signal component at the modulationfrequency of the optical source. In example embodiments, a largeadditional signal component, such as in the nA or μA range, may arisedue to visible and infrared background, display light, etc. In exampleembodiments, the relatively small signal components, with itsdistinctive temporal and/or spatial signature as provided by modulation(in time and/or space) of the illumination source, may nevertheless beisolated relative to other background/signal, and may be employed todiscern gestural information.

In embodiments, light-absorbing material 405 may consist of a materialthat principally absorbs infrared light in a certain band; and that issubstantially transparent to visible-wavelength light. In an exampleembodiment, a material such as PBDTT-DPP, the near-infraredlight-sensitive polymerpoly(2,60-4,8-bis(5-ethylhexylthienyl)benzo-[1,2-b;3,4-b]dithiophene-alt-5-dibutyloctyl-3,6-bis(5-bromothiophen-2-yl)pyrrolo[3,4-c]pyrrole-1,4-dione),may be employed as a component of the light-absorbing layer.

In embodiments, the electronic signal produced by the light sensor maybe communicated to a device for electronic amplification. This devicemay amplify a specific electronic frequency band more than other bands,producing an enhanced signal component that is related to the gesturalinformation. The signal from the light sensor, possibly with thecombination of amplification (potentially frequency-dependent), may beinput to an analog-to-digital converter that can produce a digitalsignal related to the gestural information. The digital informationrelated to gestural information can be further conveyed to otherintegrated circuits and/or signal processing engines in the context of asystem. For example, it may be conveyed to an application processor.

In embodiments, optical sources used to illuminate a volume of space,with the goal of enabling gesture recognition, may use illumination at anear infrared wavelength that is substantially unseen by the human eye.In an example embodiment, a light-emitting diode having centerwavelength of approximately 950 nm may be employed.

In embodiments, gesture recognition may be accomplished by combininginformation from at least one camera, embedded into the computingdevice, and having a lens providing a substantially focused image ontoan image sensor that is part of the camera; and may also incorporatesensors in the peripheral region, and/or integrated into the displayregion. In embodiments, the distributed sensors may provide generalinformation on the spatio-temporal movements of the object being imaged;and the signals from the at least one camera(s) may be combined with thedistributed sensors' signals to provide a morespatially-/temporally-accurate picture of the two- or three-dimensionalmotion of the object whose gesture is to be recognized. In an exampleembodiment, the camera may employ an image sensor providing a modestspatial resolution, such as QVGA, VGA, SVGA, etc., and thus beimplemented using an image sensor having small die size and thus lowcost; and also be implemented using a camera module having small x, y,and z form factor, enabling minimal consumption of peripheral regionarea, and no substantial addition to the z-height of the tablet or othercomputing device. In embodiments, a moderate frame rate, such as 15 fps,30 fps, or 60 fps may be employed, which, combined with a modestresolution, enables a low-cost digital communication channel andmoderate complexity of signal processing in the recognition of gestures.In embodiments, the at least one camera module may implement wide fieldof view imaging in order to provide a wide angular range in theassessment of gestures in relation to a display.

In embodiments, at least one camera module may be tilted, having itsangle of regard nonparallel to the normal direction (perpendiculardirection) to the display, enabling the at least one camera to image anangular extent in closer proximity to the display. In embodiments,multiple cameras may be employed in combination, each having an angle ofregard distinct from at least one another, thereby enabling gestures inmoderate proximity to the display to be imaged and interpreted. Inembodiments, the at least one camera may employ an image sensorsensitized using light-detecting materials that provide high quantumefficiency, for example, greater than 30%, at near infrared wavelengthused by the illuminating source; this enables reduced requirement forpower and/or intensity in the illuminating source.

In embodiments, the illuminating source may be modulated in time at aspecific frequency and employing a specific temporal pattern (e.g., aseries of pulses of known spacing and width in time); and the signalfrom the at least one camera and/or the at least one distributed sensormay be interpreted with knowledge of the phase and temporal profile ofthe illuminating source; and in this manner, increased signal-to-noiseratio, akin to lock-in or boxcar-averaging or other filtering and/oranalog or digital signal processing methods, may be used tosubstantially pinpoint the modulated, hence illuminated signal, andsubstantially remove or minimize the background signal associated withthe background scene.

FIG. 14 shows an embodiment of a method of gesture recognition. Themethod comprises an operation 501 that includes acquiring a stream intime of at least two images from each of at least one of the cameramodule(s); and an operation 507 that includes also acquiring a stream,in time, of at least two signals from each of at least one of the lightsensors. The method further comprises, at operations 503 and 509,conveying the images and/or signals to a processor. The method furthercomprises, at operation 505, using the processor, an estimate of agesture's meaning, and timing, based on the combination of the imagesand signals.

FIG. 15 shows an embodiment of a method of gesture recognition. Themethod comprises an operation 601 that includes acquiring a stream intime of at least two images from each of at least one of the cameramodules; and an operation 607 that includes also acquiring a stream, intime, of at least two signals from each of at least one of thetouch-based interface devices. The method further comprises, atoperations 603 and 609, conveying the images and/or signals to aprocessor. The method further comprises, at operation 605, using theprocessor, an estimate of a gesture's meaning, and timing, based on thecombination of the images and signals.

In embodiments, signals received by at least one of (1) the touch-basedinterface devices; (2) the camera modules; (3) the light sensors, eachof these either within the peripheral and/or the display ordisplay/input regions, may be employed and, singly or jointly, used todetermine the presence, and the type, of gesture indicated by a user ofthe device.

Referring again to FIG. 14, in embodiments, a stream, in time, of imagesis acquired from each of at least one of the camera modules. A stream,in time, of at least two signals from each of at least one of the lightsensors is also acquired. In embodiments, the streams may be acquiredfrom the different classes of peripheral devices synchronously. Inembodiments, the streams may be acquired with known time stampsindicating when each was acquired relative to the others, for example,to some conference reference time point. In embodiments, the streams areconveyed to a processor. The processor computes an estimate of thegesture's meaning, and timing, based on the combination of the imagesand signals.

In embodiments, at least one camera module has a wide field of viewexceeding about 40°. In embodiments, at least one camera module employsa fisheye lens. In embodiments, at least one image sensor achieveshigher resolution at its center, and lower resolution in its periphery.In embodiments, at least one image sensor uses smaller pixels near itscenter and larger pixels near its periphery.

In embodiments, active illumination via at least one light source;combined with partial reflection and/or partial scattering off of aproximate object; combined with light sensing using at least one opticalmodule or light sensor; may be combined to detect proximity to anobject. In embodiments, information regarding such proximity may be usedto reduce power consumption of the device. In embodiments, powerconsumption may be reduced by dimming, or turning off, power-consumingcomponents such as a display.

In embodiments, at least one optical source may emit infrared light. Inembodiments, at least one optical source may emit infrared light in thenear infrared between about 700 nm and about 1100 nm. In embodiments, atleast one optical source may emit infrared light in the short-wavelengthinfrared between about 1100 nm and about 1700 nm wavelength. Inembodiments, the light emitted by the optical source is substantiallynot visible to the user of the device.

In embodiments, at least one optical source may project a structuredlight image. In embodiments, spatial patterned illumination, combinedwith imaging, may be employed to estimate the relative distance ofobjects relative to the imaging system.

In embodiments, at least two lensing systems may be employed to image ascene, or portions of a scene, onto two distinct regions of amonolithically-integrated single image sensor integrated circuit; andthe patterns of light thus acquired using the image sensor integratedcircuit may be used to aid in estimating the relative or absolutedistances of objects relative to the image sensor system.

In embodiments, at least two lensing systems may be employed to image ascene, or portions of a scene, onto two distinct image sensor integratedcircuits housed within a single camera system; and the patterns of lightthus acquired using the image sensor integrated circuits may be used toaid in estimating the relative or absolute distances of objects relativeto the image sensor system.

In embodiments, at least two lensing systems may be employed to image ascene, or portions of a scene, onto two distinct image sensor integratedcircuits housed within separate camera systems or subsystems; and thepatterns of light thus acquired using the image sensor integratedcircuits may be used to aid in estimating the relative or absolutedistances of objects relative to the image sensor systems or subsystems.

In embodiments, the different angles of regard, or perspectives, fromwhich the at least two optical systems perceive the scene, may be usedto aid in estimating the relative or absolute distances of objectsrelative to the image sensor system.

In embodiments, light sensors such as the light sensors 115A, 115Bsituated in the peripheral region 101 of FIG. 10, and/or the lightsensors 107A, 107B situated in the display region 103 of FIG. 10, may beused singly, or in combination with one another, and/or in combinationwith camera modules, to acquire information about a scene. Inembodiments, light sensors may employ lenses to aid in directing lightfrom certain regions of a scene onto specific light sensors. Inembodiments, light sensors may employ systems for aperturing, such aslight-blocking housings, that define a limited angular range over whichlight from a scene will impinge on a certain light sensor. Inembodiments, a specific light sensor will, with the aid of aperturing,be responsible for sensing light from within a specific angular cone ofincidence.

In embodiments, the different angles of regard, or perspectives, fromwhich the at least two optical systems perceive the scene, may be usedto aid in estimating the relative or absolute distances of objectsrelative to the image sensor system.

In embodiments, the time sequence of light detector from at least twolight sensors may be used to estimate the direction and velocity of anobject. In embodiments, the time sequence of light detector from atleast two light sensors may be used to ascertain that a gesture was madeby a user of a computing device. In embodiments, the time sequence oflight detector from at least two light sensors may be used to classifythe gesture that was made by a user of a computing device. Inembodiments, information regarding the classification of a gesture, aswell as the estimated occurrence in time of the classified gesture, maybe conveyed to other systems or subsystems within a computing device,including to a processing unit.

In embodiments, light sensors may be integrated into the display regionof a computing device, for example, the light sensors 107A, 107B of FIG.10. In embodiments, the incorporation of the light sensors into thedisplay region can be achieved without the operation of the display inthe conveyance of visual information to the user being substantiallyaltered. In embodiments, the display may convey visual information tothe user principally using visible wavelengths in the range of about 400nm to about 650 nm, while the light sensors may acquire visualinformation regarding the scene principally using infrared light ofwavelengths longer than about 650 nm. In embodiments, a ‘display plane’operating principally in the visible wavelength region may reside infront of—closer to the user—than a ‘light sensing plane’ that mayoperate principally in the infrared spectral region.

In embodiments, structured light of a first type may be employed, and ofa second type may also be employed, and the information from the atleast two structured light illuminations may be usefully combined toascertain information regarding a scene that exceeds the informationcontained in either isolated structured light image.

In embodiments, structured light of a first type may be employed toilluminate a scene and may be presented from a first source providing afirst angle of illumination; and structured light of a second type maybe employed to illuminate a scene and may be presented from a secondsource providing a second angle of illumination.

In embodiments, structured light of a first type and a first angle ofillumination may be sensed using a first image sensor providing a firstangle of sensing; and also using a second image sensor providing asecond angle of sensing.

In embodiments, structured light having a first pattern may be presentedfrom a first source; and structured light having a second pattern may bepresented from a second source.

In embodiments, structured light having a first pattern may be presentedfrom a source during a first time period; and structured light having asecond pattern may be presented from a source during a second timeperiod.

In embodiments, structured light of a first wavelength may be used toilluminate a scene from a first source having a first angle ofillumination; and structured light of a second wavelength may be used toilluminate a scene from a second source having a second angle ofillumination.

In embodiments, structured light of a first wavelength may be used toilluminate a scene using a first pattern; and structured light of asecond wavelength may be used to illuminate a scene using a secondpattern. In embodiments, a first image sensor may sense the scene with astrong response at the first wavelength and a weak response at thesecond wavelength; and a second image sensor may sense the scene with astrong response at the second wavelength and a weak response at thefirst wavelength. In embodiments, an image sensor may consist of a firstclass of pixels having strong response at the first wavelength and weakresponse at the second wavelength; and of a second class of pixelshaving strong response at the second wavelength and weak response at thefirst wavelength.

Embodiments include image sensor systems that employ a filter having afirst bandpass spectral region; a first bandblock spectral region; and asecond bandpass spectral region. Embodiments include the first bandpassregion corresponding to the visible spectral region; the first bandblockspectral region corresponding to a first portion of the infrared; andthe second bandpass spectral region corresponding to a second portion ofthe infrared. Embodiments include using a first time period to detectprimarily the visible-wavelength scene; and using active illuminationwithin the second bandpass region during a second time period to detectthe sum of a visible-wavelength scene and an actively-illuminatedinfrared scene; and using the difference between images acquired duringthe two time periods to infer a primarily actively-illuminated infraredscene. Embodiments include using structured light during the second timeperiod. Embodiments include using infrared structured light. Embodimentsinclude using the structured light images to infer depth informationregarding the scene; and in tagging, or manipulating, the visible imagesusing information regarding depth acquired based on the structured lightimages.

In embodiments, gestures inferred may include one-thumb-up;two-thumbs-up; a finger swipe; a two-finger swipe; a three-finger swipe;a four-finger-swipe; a thumb plus one finger swipe; a thumb plus twofinger swipe; etc. In embodiments, gestures inferred may includemovement of a first digit in a first direction; and of a second digit ina substantially opposite direction. Gestures inferred may include atickle.

Sensing of the intensity of light incident on an object may be employedin a number of applications. One such application includes estimation ofambient light levels incident upon an object so that the object's ownlight-emission intensity can be suitable selected. In mobile devicessuch as cell phones, personal digital assistants, smart phones, and thelike, the battery life, and thus the reduction of the consumption ofpower, are of importance. At the same time, the visual display ofinformation, such as through the use of a display such as those based onLCDs or pixellated LEDs, may also be needed. The intensity with whichthis visual information is displayed depends at least partially on theambient illumination of the scene. For example, in very bright ambientlighting, more light intensity generally needs to be emitted by thedisplay in order for the display's visual impression or image to beclearly visible above the background light level. When ambient lightingis weaker, it is feasible to consume less battery power by emitting alower level of light from the display.

As a result, it is of interest to sense the light level near or in thedisplay region. Existing methods of light sensing often include asingle, or a very few, light sensors, often of small area. This can leadto undesired anomalies and errors in the estimation of ambientillumination levels, especially when the ambient illumination of thedevice of interest is spatially inhomogeneous. For example, shadows dueto obscuring or partially obscuring objects may—if they obscure one or afew sensing elements—result in a display intensity that is less brightthan desirable under the true average lighting conditions.

Embodiments include realization of a sensor, or sensors, that accuratelypermit the determination of light levels. Embodiments include at leastone sensor realized using solution-processed light-absorbing materials.Embodiments include sensors in which colloidal quantum dot filmsconstitute the primary light-absorbing element. Embodiments includesystems for the conveyance of signals relating to the light levelimpinging on the sensor that reduce, or mitigate, the presence of noisein the signal as it travels over a distance between a passive sensor andactive electronics that employ the modulation of electrical signals usedin transduction. Embodiments include systems that include (1) thelight-absorbing sensing element; (2) electrical interconnect for theconveyance of signals relating to the light intensity impinging upon thesensing element; and (3) circuitry that is remote from thelight-absorbing sensing element, and is connected to it via theelectrical interconnect, that achieves low-noise conveyance of thesensed signal through the electrical interconnect. Embodiments includesystems in which the length of interconnect is more than one centimeterin length. Embodiments include systems in which interconnect does notrequire special shielding yet achieve practically useful signal-to-noiselevels.

Embodiments include sensors, or sensor systems, that are employed,singly or in combination, to estimate the average color temperatureilluminating the display region of a computing device. Embodimentsinclude sensors, or sensor systems, that accept light from a wideangular range, such as greater than about ±20° to normal incidence, orgreater than about ±30° to normal incidence, or greater than about ±40°to normal incidence. Embodiments include sensors, or sensor systems,that include at least two types of optical filters, a first type passingprimarily a first spectral band, a second type passing primarily asecond spectral band. Embodiments include using information from atleast two sensors employing at least two types of optical filters toestimate color temperature illuminating the display region, or a regionproximate the display region.

Embodiments include systems employing at least two types of sensors.Embodiments include a first type constituted of a first light-sensingmaterial, and a second type constituted of a second light-sensingmaterial. Embodiments include a first light-sensing material configuredto absorb, and transduce, light in a first spectral band, and a secondlight-sensing material configured to transduce a second spectral band.Embodiments include a first light-sensing material employing a pluralityof nanoparticles having a first average diameter, and a secondlight-sensing material employing a plurality of nanoparticles have asecond average diameter. Embodiments include a first diameter in therange of approximately 1 nm to approximately 2 nm, and a second diametergreater than about 2 nm.

Embodiments include methods of incorporating a light-sensing materialinto, or onto, a computing device involving inkjet printing. Embodimentsinclude using a nozzle to apply light-sensing material over a definedregion. Embodiments include defining a primary light-sensing regionusing electrodes. Embodiments include methods of fabricating lightsensing devices integrated into, or onto, a computing device involving:defining a first electrode; defining a second electrode; defining alight-sensing region in electrical communication with the first and thesecond electrode. Embodiments include methods of fabricating lightsensing devices integrated into, or onto, a computing device involving:defining a first electrode; defining a light-sensing region; anddefining a second electrode; where the light sensing region is inelectrical communication with the first and the second electrode.

Embodiments include integration at least two types of sensors into, oronto, a computing device, using ink-jet printing. Embodiments includeusing a first reservoir containing a first light-sensing materialconfigured to absorb, and transduce, light in a first spectral band; andusing a second reservoir containing a second light-sensing materialconfigured to absorb, and transduce, light in a second spectral band.

Embodiments include the use of differential or modulated signaling inorder to substantially suppress any external interference. Embodimentsinclude subtracting dark background noise.

Embodiments include a differential system depicted in FIG. 16. FIG. 16shows an embodiment of a three-electrode differential-layout system 700to reduce external interferences with light sensing operations. Thethree-electrode differential-layout system 700 is shown to include alight sensing material covering all three electrodes 701, 703, 705. Alight-obscuring material 707 (Black) prevents light from impinging uponthe light-sensing material in a region that is electrically accessedusing the first electrode 701 and the second electrode 703. Asubstantially transparent material 709 (Clear) allows light to impingeupon the light-sensing material in a substantially distinct region thatis electrically accessed using the second electrode 703 and the thirdelectrode 705. The difference in the current flowing through theClear-covered electrode pair and the Black-covered electrode pair isequal to the photocurrent—that is, this difference does not include anydark current, but instead is proportional to the light intensity, withany dark offset substantially removed.

Embodiments include the use of a three-electrode system as follows. Eachelectrode consists of a metal wire. Light-absorbing material may be inelectrical communication with the metal wires. Embodiments include theencapsulation of the light-absorbing material using a substantiallytransparent material that protects the light-absorbing material fromambient environmental conditions such as air, water, humidity, dust, anddirt. The middle of the three electrodes may be biased to a voltage V₁,where an example of a typical voltage is about 0 V. The two outerelectrodes may be biased to a voltage V₂, where a typical value is about3 V. Embodiments include covering a portion of the device usinglight-obscuring material that substantially prevents, or reduces, theincidence of light on the light-sensing material.

The light-obscuring material ensures that one pair of electrodes seeslittle or no light. This pair is termed the dark, or reference,electrode pair. The use of a transparent material over the otherelectrode pair ensures that, if light is incident, it is substantiallyincident upon the light-sensing material. This pair is termed the lightelectrode pair.

The difference in the current flowing through the light electrode pairand the dark electrode pair is equal to the photocurrent—that is, thisdifference does not include any dark current, but instead isproportional to the light intensity, with any dark offset substantiallyremoved.

In embodiments, these electrodes are wired in twisted-pair form. In thismanner, common-mode noise from external sources is reduced or mitigated.Referring to FIG. 17, electrodes 801, 803, 805 with twisted pair layout800, the use of a planar analogue of a twisted-pair configuration leadsto reduction or mitigation of common-mode noise from external sources.

In another embodiment, biasing may be used such that the light-obscuringlayer may not be required. The three electrodes may be biased to threevoltages V₁, V₂, and V₃. In one example, V₁=6 V, V₂=3 V, V₃=0 V. Thelight sensor between 6 V and 3 V, and that between 0 V and 3 V, willgenerate opposite-direction currents when read between the 6 V and 0 V.The resultant differential signal is then transferred out intwisted-pair fashion.

In embodiments, the electrode layout may itself be twisted, furtherimproving the noise-resistance inside the sensor. In this case, anarchitecture is used in which an electrode may cross over another.

In embodiments, electrical bias modulation may be employed. Analternating bias may be used between a pair of electrodes. Thephotocurrent that flows will substantially mimic the temporal evolutionof the time-varying electrical biasing. Readout strategies includefiltering to generate a low-noise electrical signal. The temporalvariations in the biasing include sinusoidal, square, or other periodicprofiles. For example, referring to FIG. 18, an embodiment oftime-modulated biasing 900 a signal 901 applied to electrodes to reduceexternal noise that is not at the modulation frequency. Modulating thesignal in time allows rejection of external noise that is not at themodulation frequency.

Embodiments include combining the differential layout strategy with themodulation strategy to achieve further improvements in signal-to-noiselevels.

Embodiments include employing a number of sensors having differentshapes, sizes, and spectral response (e.g., sensitivities to differentcolors). Embodiments include generating multi-level output signals.Embodiments include processing signals using suitable circuits andalgorithms to reconstruct information about the spectral and/or otherproperties of the light incident.

Advantages of the disclosed subject matter include transfer of accurateinformation about light intensity over longer distances than wouldotherwise be possible. Advantages include detection of lower levels oflight as a result. Advantages include sensing a wider range of possiblelight levels. Advantages include successful light intensitydetermination over a wider range of temperatures, an advantageespecially conferred when the dark reference is subtracted using thedifferential methods described herein.

Embodiments include a light sensor including a first electrode, a secondelectrode, and a third electrode. A light-absorbing semiconductor is inelectrical communication with each of the first, second, and thirdelectrodes. A light-obscuring material substantially attenuates theincidence of light onto the portion of light-absorbing semiconductorresiding between the second and the third electrodes, where anelectrical bias is applied between the second electrode and the firstand third electrodes and where the current flowing through the secondelectrode is related to the light incident on the sensor.

Embodiments include a light sensor including a first electrode, a secondelectrode, and a light-absorbing semiconductor in electricalcommunication with the electrodes wherein a time-varying electrical biasis applied between the first and second electrodes and wherein thecurrent flowing between the electrodes is filtered according to thetime-varying electrical bias profile, wherein the resultant component ofcurrent is related to the light incident on the sensor.

Embodiments include the above embodiments where the first, second, andthird electrodes consists of a material chosen from the list: gold,platinum, palladium, silver, magnesium, manganese, tungsten, titanium,titanium nitride, titanium dioxide, titanium oxynitride, aluminum,calcium, and lead.

Embodiments include the above embodiments where the light-absorbingsemiconductor includes materials taken from the list: PbS, PbSe, PbTe,SnS, SnSe, SnTe, CdS, CdSe, CdTe, Bi₂S₃, In₂S₃, In₂S₃, In₂Te₃, ZnS,ZnSe, ZnTe, Si, Ge, GaAs, polypyrolle, pentacene, polyphenylenevinylene,polyhexylthiophene, and phenyl-C61-butyric acid methyl ester.

Embodiments include the above embodiments where the bias voltages aregreater than about 0.1 V and less than about 10 V. Embodiments includethe above embodiments where the electrodes are spaced a distance betweenabout 1 μm and about 20 μm from one another.

Embodiments include the above embodiments where the distance between thelight-sensing region and active circuitry used in biasing and reading isgreater than about 1 cm and less than about 30 cm.

The capture of visual information regarding a scene, such as viaimaging, is desired in a range of areas of application. In cases, theoptical properties of the medium residing between the imaging system,and the scene of interest, may exhibit optical absorption, opticalscattering, or both. In cases, the optical absorption and/or opticalscattering may occur more strongly in a first spectral range compared toa second spectral range. In cases, the strongly-absorbing-or-scatteringfirst spectral range may include some or all of the visible spectralrange of approximately 470 nm to approximately 630 nm, and themore-weakly-absorbing-or-scattering second spectral range may includeportions of the infrared spanning a range of approximately 650 nm toapproximately 24 μm wavelengths.

In embodiments, image quality may be augmented by providing an imagesensor array having sensitivity to wavelengths longer than about a 650nm wavelength.

In embodiments, an imaging system may operate in two modes: a first modefor visible-wavelength imaging; and a second mode for infrared imaging.In embodiments, the first mode may employ a filter that substantiallyblocks the incidence of light of some infrared wavelengths onto theimage sensor.

Referring now to FIG. 19, an embodiment of a transmittance spectrum 1000of a filter that may be used in various imaging applications.Wavelengths in the visible spectral region 1001 are substantiallytransmitted, enabling visible-wavelength imaging. Wavelengths in theinfrared bands 1003 of approximately 750 nm to approximately 1450 nm,and also in a region 1007 beyond about 1600 nm, are substantiallyblocked, reducing the effect of images associated with ambient infraredlighting. Wavelengths in the infrared band 1005 of approximately 1450 nmto approximately 1600 nm are substantially transmitted, enablinginfrared-wavelength imaging when an active source having its principalspectral power within this band is turned on.

In embodiments, an imaging system may operate in two modes: a first modefor visible-wavelength imaging; and a second mode for infrared imaging.In embodiments, the system may employ an optical filter, which remainsin place in each of the two modes, that substantially blocks incidenceof light over a first infrared spectral band; and that substantiallypasses incidence of light over a second infrared spectral band. Inembodiments, the first infrared spectral band that is blocked may spanfrom about 700 nm to about 1450 nm. In embodiments, the second infraredspectral band that is substantially not blocked may begin at about 1450nm. In embodiments, the second infrared spectral band that issubstantially not blocked may end at about 1600 nm. In embodiments, inthe second mode for infrared imaging, active illuminating that includespower in the second infrared spectral band that is substantially notblocked may be employed. In embodiments, a substantiallyvisible-wavelength image may be acquired via image capture in the firstmode. In embodiments, a substantially actively-infrared-illuminatedimage may be acquired via image capture in the second mode. Inembodiments, a substantially actively-infrared-illuminated image may beacquired via image capture in the second mode aided by the subtractionof an image acquired during the first mode. In embodiments, aperiodic-in-time alternation between the first mode and second mode maybe employed. In embodiments, a periodic-in-time alternation betweenno-infrared-illumination, and active-infrared-illumination, may beemployed. In embodiments, a periodic-in-time alternation betweenreporting a substantially visible-wavelength image, and reporting asubstantially actively-illuminated-infrared image, may be employed. Inembodiments, a composite image may be generated which displays, inoverlaid fashion, information relating to the visible-wavelength imageand the infrared-wavelength image. In embodiments, a composite image maybe generated which uses a first visible-wavelength color, such as blue,to represent the visible-wavelength image; and uses a secondvisible-wavelength color, such as red, to represent theactively-illuminated infrared-wavelength image, in a manner that isoverlaid.

In image sensors, a nonzero, nonuniform, image may be present even inthe absence of illumination, (in the dark). If not accounted for, thedark images can lead to distortion and noise in the presentation ofilluminated images.

In embodiments, an image may be acquired that represents the signalpresent in the dark. In embodiments, an image may be presented at theoutput of an imaging system that represents the difference between anilluminated image and the dark image. In embodiments, the dark image maybe acquired by using electrical biasing to reduce the sensitivity of theimage sensor to light. In embodiments, an image sensor system may employa first time interval, with a first biasing scheme, to acquire asubstantially dark image; and a second time interval, with a secondbiasing scheme, to acquire a light image. In embodiments, the imagesensor system may store the substantially dark image in memory; and mayuse the stored substantially dark image in presenting an image thatrepresents the difference between a light image and a substantially darkimage. Embodiments include reducing distortion, and reducing noise,using the method.

In embodiments, a first image may be acquired that represents the signalpresent following reset; and a second image may be acquired thatrepresents the signal present following an integration time; and animage may be presented that represents the difference between the twoimages. In embodiments, memory may be employed to store at least one oftwo of the input images. In embodiments, the result difference image mayprovide temporal noise characteristics that are consistent withcorrelated double-sampling noise. In embodiments, an image may bepresented having equivalent temporal noise considerable less than thatimposed by sqrt(kTC) noise.

Embodiments include high-speed readout of a dark image; and of a lightimage; and high-speed access to memory and high-speed image processing;to present a dark-subtracted image to a user rapidly.

Embodiments include a camera system in which the interval between theuser indicating that an image is to be acquired; and in which theintegration period associated with the acquisition of the image; is lessthan about one second. Embodiments include a camera system that includesa memory element in between the image sensor and the processor.

Embodiments include a camera system in which the time in between shotsis less than about one second.

Embodiments include a camera system in which a first image is acquiredand stored in memory; and a second image is acquired; and a processor isused to generate an image that employs information from the first imageand the second image. Embodiments include generating an image with highdynamic range by combining information from the first image and thesecond image. Embodiments include a first image having a first focus;and a second image having a second focus; and generating an image fromthe first image and the second image having higher equivalent depth offocus.

Hotter objects generally emit higher spectral power density at shorterwavelengths than do colder objects. Information may thus be extractedregarding the relative temperatures of objects imaged in a scene basedon the ratios of power in a first band to the power in a second band.

In embodiments, an image sensor may comprise a first set of pixelsconfigured to sense light primarily within a first spectral band; and asecond set of pixels configured to sense light primarily within a secondspectral band. In embodiments, an inferred image may be reported thatcombines information from proximate pixels of the first and second sets.In embodiments, an inferred image may be reported that provides theratio of signals from proximate pixels of the first and second sets.

In embodiments, an image sensor may include a means of estimating objecttemperature; and may further include a means of acquiringvisible-wavelength images. In embodiments, image processing may be usedto false-color an image representing estimated relative objecttemperature atop a visible-wavelength image.

In embodiments, the image sensor may include at least one pixel havinglinear dimensions less than approximately 2 μm×2 μm.

In embodiments, the image sensor may include a first layer providingsensing in a first spectral band; and a second layer providing sensingin a second spectral band.

In embodiments, visible images can be used to present a familiarrepresentation to users of a scene; and infrared images can provideadded information, such as regarding temperature, or pigment, or enablepenetration through scattering and/or visible-absorbing media such asfog, haze, smoke, or fabrics.

In cases, it may be desired to acquire both visible and infrared imagesusing a single image sensor. In cases, registration among visible andinfrared images is thus rendered substantially straightforward.

In embodiments, an image sensor may employ a single class oflight-absorbing light-sensing material; and may employ a patterned layerabove it that is responsible for spectrally-selective transmission oflight through it, also known as a filter. In embodiments, thelight-absorbing light-sensing material may providehigh-quantum-efficiency light sensing over both the visible and at leasta portion of the infrared spectral regions. In embodiments, thepatterned layer may enable both visible-wavelength pixel regions, andalso infrared-wavelength pixel regions, on a single image sensorcircuit.

In embodiments, an image sensor may employ two classes oflight-absorbing light-sensing materials: a first material configured toabsorb and sense a first range of wavelengths; and a second materialconfigured to absorb and sense a second range of wavelengths. The firstand second ranges may be at least partially overlapping, or they may notbe overlapping.

In embodiments, two classes of light-absorbing light-sensing materialsmay be placed in different regions of the image sensor. In embodiments,lithography and etching may be employed to define which regions arecovered using which light-absorbing light-sensing materials. Inembodiments, ink jet printing may be employed to define which regionsare covered using which light-absorbing light-sensing materials.

In embodiments, two classes of light-absorbing light-sensing materialsmay be stacked vertically atop one another. In embodiments, a bottomlayer may sense both infrared and visible light; and a top layer maysense visible light principally.

In embodiments, an optically-sensitive device may include: a firstelectrode; a first light-absorbing light-sensing material; a secondlight-absorbing light-sensing material; and a second electrode. Inembodiments, a first electrical bias may be provided between the firstand second electrodes such that photocarriers are efficiently collectedprimarily from the first light-absorbing light-sensing material. Inembodiments, a second electrical bias may be provided between the firstand second electrodes such that photocarriers are efficiently collectedprimarily from the second light-absorbing light-sensing material. Inembodiments, the first electrical bias may result in sensitivityprimarily to a first wavelength of light. In embodiments, the secondelectrical bias may result in sensitivity primarily to a secondwavelength of light. In embodiments, the first wavelength of light maybe infrared; and the second wavelength of light may be visible. Inembodiments, a first set of pixels may be provided with the first bias;and a second set of pixels may be provided with the second bias;ensuring that the first set of pixels responds primarily to a firstwavelength of light, and the second set of pixels responds primarily toa second wavelength of light.

In embodiments, a first electrical bias may be provided during a firstperiod of time; and a second electrical bias may be provided during asecond period of time; such that the image acquired during the firstperiod of time provides information primarily regarding a firstwavelength of light; and the image acquired during the second period oftime provides information primarily regarding a second wavelength oflight. In embodiments, information acquired during the two periods oftime may be combined into a single image. In embodiments, false-colormay be used to represent, in a single reported image, informationacquired during each of the two periods of time.

In embodiments, a focal plane array may consist of a substantiallylaterally-spatially uniform film having a substantiallylaterally-uniform spectral response at a given bias; and having aspectral response that depends on the bias. In embodiments, a spatiallynonuniform bias may be applied, for example, different pixel regions maybias the film differently. In embodiments, under a givenspatially-dependent biasing configuration, different pixels may providedifferent spectral responses. In embodiments, a first class of pixelsmay be responsive principally to visible wavelengths of light, while asecond class of pixels may be responsive principally to infraredwavelengths of light. In embodiments, a first class of pixels may beresponsive principally to one visible-wavelength color, such as blue;and a second class of pixels may be responsive principally to adistinctive visible-wavelength color, such as green; and a third classof pixels may be responsive principally to a distinctivevisible-wavelength color, such as red.

In embodiments, an image sensor may comprise a readout integratedcircuit, at least one pixel electrode of a first class, at least onepixel electrode of a second class, a first layer of optically sensitivematerial, and a second layer of optically sensitive material. Inembodiments, the image sensor may employ application of a first bias forthe first pixel electrode class; and of a second bias to the secondpixel electrode class.

In embodiments, those pixel regions corresponding to the first pixelelectrode class may exhibit a first spectral response; and of the secondpixel electrode class may exhibit a second spectral response; where thefirst and second spectral responses are significantly different. Inembodiments, the first spectral response may be substantially limited tothe visible-wavelength region. In embodiments, the second spectralresponse may be substantially limited to the visible-wavelength region.In embodiments, the second spectral response may include both portionsof the visible and portions of the infrared spectral regions.

In embodiments, it may be desired to fabricate an image sensor havinghigh quantum efficiency combined with low dark current.

In embodiments, a device may consist of: a first electrode; a firstselective spacer; a light-absorbing material; a second selective spacer;and a second electrode.

In embodiments, the first electrode may be used to extract electrons. Inembodiments, the first selective spacer may be used to facilitate theextraction of electrons but block the injection of holes. Inembodiments, the first selective spacer may be an electron-transportlayer. In embodiments, the light-absorbing material may includesemiconductor nanoparticles. In embodiments, the second selective spacermay be used to facilitate the extraction of holes but block theinjection of electrons. In embodiments, the second selective spacer maybe a hole-transport layer.

In embodiments, only a first selective spacer may be employed. Inembodiments, the first selective spacer may be chosen from the list:TiO₂, ZnO, and ZnS. In embodiments, the second selective spacer may beNiO. In embodiments, the first and second electrode may be made usingthe same material. In embodiments, the first electrode may be chosenfrom the list: TiN, W, Al, and Cu. In embodiments, the second electrodemay be chosen from the list: ZnO, Al:ZnO, ITO, MoO₃, Pedot, andPedot:PSS.

In embodiments, it may be desired to implement an image sensor in whichthe light-sensing element can be configured during a first interval toaccumulate photocarriers; and during a second interval to transferphotocarriers to another node in a circuit.

Embodiments include a device comprising: a first electrode; a lightsensing material; a blocking layer; and a second electrode.

Embodiments include electrically biasing the device during a firstinterval, known as the integration period, such that photocarriers aretransported towards the first blocking layer; and where photocarriersare stored near the interface with the blocking layer during theintegration period.

Embodiments include electrically biasing the device during a secondinterval, known as the transfer period, such that the storedphotocarriers are extracted during the transfer period into another nodein a circuit.

Embodiments include a first electrode chosen from the list: TiN, W, Al,Cu. In embodiments, the second electrode may be chosen from the list:ZnO, Al:ZnO, ITO, MoO3, Pedot, and Pedot:PSS. In embodiments, theblocking layer be chosen from the list: HfO₂, Al₂O₃, NiO, TiO₂, and ZnO.

In embodiments, the bias polarity during the integration period may beopposite to that during the transfer period. In embodiments, the biasduring the integration period may be of the same polarity as that duringthe transfer period. In embodiments, the amplitude of the bias duringthe transfer period may be greater than that during the integrationperiod.

Embodiments include a light sensor in which an optically sensitivematerial functions as the gate of a silicon transistor. Embodimentsinclude devices comprising: a gate electrode coupled to a transistor; anoptically sensitive material; a second electrode. Embodiments includethe accumulation of photoelectrons at the interface between the gateelectrode and the optically sensitive material. Embodiments include theaccumulation of photoelectrons causing the accumulation of holes withinthe channel of the transistor. Embodiments include a change in the flowof current in the transistor as a result of a change in photoelectronsas a result of illumination. Embodiments include a change in currentflow in the transistor greater than 1000 electrons/s for everyelectron/s of change in the photocurrent flow in the optically sensitivelayer. Embodiments include a saturation behavior in which the transistorcurrent versus photons impinged transfer curve has a sublineardependence on photon fluence, leading to compression and enhanceddynamic range. Embodiments include resetting the charge in the opticallysensitive layer by applying a bias to a node on the transistor thatresults in current flow through the gate during the reset period.

Embodiments include combinations of the above image sensors, camerasystems, fabrication methods, algorithms, and computing devices, inwhich at least one image sensor is capable of operating in globalelectronic shutter mode.

In embodiments, at least two image sensors, or image sensor regions, mayeach operate in global shutter mode, and may provide substantiallysynchronous acquisition of images of distinct wavelengths, or fromdifferent angles, or employing different structured light.

Embodiments include implementing correlated double-sampling in theanalog domain. Embodiments include so doing using circuitry containedwithin each pixel. FIG. 20 shows an example schematic diagram of acircuit 1100 that may be employed within each pixel to reduce noisepower. In embodiments, a first capacitor 1101 (C₁) and a secondcapacitor 1103 (C₂) are employed in combination as shown. Inembodiments, the noise power is reduced according to the ratio C₂/C₁.

FIG. 21 shows an example schematic diagram of a circuit 1200 of aphotoGate/pinned-diode storage that may be implemented in silicon. Inembodiments, the photoGate/pinned-diode storage in silicon isimplemented as shown. In embodiments, the storage pinned diode is fullydepleted during reset. In embodiments, C₁ (corresponding to the lightsensor's capacitance, such as quantum dot film in embodiments) sees aconstant bias.

In embodiments, light sensing may be enabled through the use of a lightsensing material that is integrated with, and read using, a readoutintegrated circuit. Example embodiments of same are included in U.S.Provisional Application No. 61/352,409, entitled, “Stable, SensitivePhotodetectors and Image Sensors Made Therefrom Including Circuits forEnhanced Image Performance,” and U.S. Provisional Application No.61/352,410, entitled, “Stable, Sensitive Photodetectors and ImageSensors Made Therefrom Including Processes and Materials for EnhancedImage Performance,” both filed Jun. 8, 2010, which are herebyincorporated by reference in their entirety.

In embodiments, a method of gesture recognition is provided where themethod includes acquiring a stream, in time, of at least two images fromeach of at least one camera module; acquiring a stream, in time, of atleast two signals from each of at least one light sensor; and conveyingthe at least two images and the at least two signals to a processor, theprocessor being configured to generate an estimate of a gesture'smeaning, and timing, based on a combination of the at least two imagesand the at least two signals.

In embodiments, the at least one light sensor includes a light-absorbingmaterial having an absorbance, across the visible wavelength region ofabout 450 nm to about 650 nm, of less than about 30%.

In embodiments, the light-absorbing material includes PBDTT-DPP, thenear-infrared light-sensitive polymerpoly(2,60-4,8-bis(5-ethylhexylthienyl)benzo-[1,2-b;3,4-b]dithiophene-alt-5-dibutyloctyl-3,6-bis(5-bromothiophen-2-yl)pyrrolo[3,4-c]pyrrole-1,4-dione).

In embodiments, the at least one light sensor includes a light-sensingmaterial capable of sensing infrared light.

In embodiments, the method includes modulating a light source using atleast one code selected from spatial codes and temporal codes.

In embodiments, the light source has an emission wavelength in the rangeof about 900 nm to about 1000 nm.

In one embodiment, a camera system includes a central imaging arrayregion, at least one light-sensing region outside of the central imagingarray region, a first mode, referred to as imaging mode, and a secondmode, referred to as sensing mode. The electrical power consumed in thesecond mode is at least 10 times lower than the electrical powerconsumed in the first mode.

In embodiments, the at least one light sensor includes a light-sensingmaterial capable of sensing infrared light.

In embodiments, light impinging on the light-sensing material is to bemodulated.

In embodiments, a portion of light impinging on the light-sensingmaterial is to be generated using a light emitter device having anemission wavelength in the range of about 800 nm to about 1000 nm.

In embodiments, the central imaging array includes at least sixmegapixels.

In embodiments, the central imaging array comprises pixels less thanapproximately 2 μm in width and approximately 2 μm in height.

In one embodiment, an image sensor circuit includes a central imagingarray region having a first field of view; and at least onelight-sensing region outside of the central imaging array region havinga second field of view. The second field of view is less than half,measured in angle, the field of view of the first field of view.

In one embodiment, an integrated circuit includes a substrate, an imagesensing array region occupying a first region of said semiconductorsubstrate and including a plurality of optically sensitive pixelregions, a pixel circuit for each pixel region, each pixel circuitcomprising a charge store and a read-out circuit, and a light-sensitiveregion outside of the image sensing array region. The image sensingarray region having a first field of view and the light-sensitive regionhaving a second field of view; the angle of the second field of view isless than half of the angle of the first field of view.

In embodiments, at least one of the image sensing array and thelight-sensitive region outside of the image sensing array regionincludes a light-sensing material capable of sensing infrared light.

In embodiments, light impinging on at least one of the image sensingarray and the light-sensitive region outside of the image sensing arrayregion is to be modulated.

In embodiments, a portion of light impinging on at least one of theimage sensing array and the light-sensitive region outside of the imagesensing array region is to be generated using a light emitter devicehaving an emission wavelength in the range of about 800 nm to about 1000nm.

In embodiments, the image sensing array includes at least sixmegapixels.

In embodiments, the image sensing array comprises pixels less thanapproximately 2 μm in width and approximately 2 μm in height.

In one embodiment, an image sensor includes a central imaging arrayregion to provide pixelated sensing of an image, in communication with aperipheral region that includes circuitry to provide biasing, readout,analog-to-digital conversion, and signal conditioning to the pixelatedlight sensing region. An optically sensitive material overlies theperipheral region.

In embodiments, the at least one light sensor includes a light-sensingmaterial capable of sensing infrared light.

In embodiments, light impinging on the light-sensing material is to bemodulated.

In embodiments, a portion of light impinging on the light-sensingmaterial is to be generated using a light emitter device having anemission wavelength in the range of about 800 nm to about 1000 nm.

In embodiments, the central imaging array includes at least sixmegapixels.

In embodiments, the central imaging array comprises pixels less thanapproximately 2 μm in width and approximately 2 μm in height.

In embodiments, the optically sensitive material is chosen to include atleast one material from a list, the list including silicon, colloidalquantum dot film, and a semiconducting polymer.

In embodiments, the optically sensitive material is fabricated on afirst substrate, and is subsequently incorporated onto the centralimaging array region.

A person of ordinary skill in the art will appreciate that, for this andother processing methods and devices disclosed herein, the activitiesforming part of various methods may, in certain cases, be implemented ina differing order, as well as repeated, executed simultaneously, orsubstituted one for another. Further, the outlined acts and operationsare only provided as examples, and some of the acts and operations maybe optional, combined into fewer acts and operations, or expanded intoadditional acts and operations without detracting from the essence ofthe disclosed embodiments. Also, various ones of the embodiments may becombined together or used separately.

The present disclosure is therefore not to be limited in terms of theparticular embodiments described in this application, which are intendedas illustrations of various aspects. Many modifications and variationscan be made, as will be apparent to a person of ordinary skill in theart upon reading and understanding the disclosure. Functionallyequivalent methods and apparatuses within the scope of the disclosure,in addition to those enumerated herein, will be apparent to a person ofordinary skill in the art from the foregoing descriptions. Portions andfeatures of some embodiments may be included in, or substituted for,those of others. Many other embodiments will be apparent to those ofordinary skill in the art upon reading and understanding the descriptionprovided herein. Such modifications and variations are intended to fallwithin a scope of the appended claims. The present disclosure is to belimited only by the terms of the appended claims, along with the fullscope of equivalents to which such claims are entitled. It is also to beunderstood that the terminology used herein is for the purpose ofdescribing particular embodiments only and is not intended to belimiting.

In addition, in the foregoing Detailed Description, it may be seen thatvarious features are grouped together in a single embodiment for thepurpose of streamlining the disclosure. This method of disclosure is notto be interpreted as limiting the claims. Thus, the following claims arehereby incorporated into the Detailed Description, with each claimstanding on its own as a separate embodiment.

The various illustrations of the procedures and apparatuses are intendedto provide a general understanding of the structure of variousembodiments and are not intended to provide a complete description ofall the elements and features of the apparatuses and methods that mightmake use of the structures, features, and materials described herein.Based upon a reading and understanding of the disclosed subject matterprovided herein, a person of ordinary skill in the art can readilyenvision other combinations and permutations of the various embodiments.The additional combinations and permutations are all within a scope ofthe disclosed subject matter.

The Abstract of the disclosure is provided to allow the reader toquickly ascertain the nature of the technical disclosure. The abstractis submitted with the understanding that it will not be used tointerpret or limit the claims. In addition, in the foregoing DetailedDescription, it may be seen that various features are grouped togetherin a single embodiment for the purpose of streamlining the disclosure.This method of disclosure is not to be interpreted as limiting theclaims. Thus, the following claims are hereby incorporated into theDetailed Description, with each claim standing on its own as a separateembodiment.

What is claimed is:
 1. An image sensor, comprising: a first pixel regioncomprising a pixel electrode, an optically sensitive material of a firstthickness, and a counterelectrode; a second pixel region comprising apixel electrode, an optically sensitive material of a second thickness,and a counterelectrode; the first pixel region is configured to detectlight in a first spectral band; the second pixel region is configured todetect light in a second spectral band; and the first and secondspectral bands include an overlapping spectral range, the secondspectral band also includes a spectral range that is substantiallyundetectable by the first pixel region.
 2. The image sensor of claim 1,wherein the optically sensitive layer comprises at least onesemiconductor nanoparticle.
 3. The image sensor of claim 1, wherein thefirst spectral band includes the range of about 450 nm to about 490 nmand the second spectral band includes the range of about 450 nm to about570 nm.
 4. The image sensor of claim 1, wherein the first spectral bandincludes the range of about 450 nm to about 490 nm and the secondspectral band includes the range of about 450 nm to about 570 nm.
 5. Theimage sensor of claim 1, wherein the first spectral band includes therange of about 450 nm to about 570 nm and the second spectral bandincludes the range of about 450 nm to about 630 nm.
 6. The image sensorof claim 1, wherein the first spectral band includes the range of about450 nm to about 630 nm and the second spectral band includes the rangeof about 450 nm to about 960 nm.
 7. The image sensor of claim 1, whereinthe first spectral band includes the range of about 450 nm to about 960nm and the second spectral band includes the range of about 450 nm toabout 1600 nm.
 8. A method of making an image sensor, the methodcomprising: producing an integrated circuit including trenches of afirst depth defining a first class of pixel regions; and trenches of asecond depth defining a second class of pixel regions; overcoating thetrenched integrated circuit with a substantially planarizing opticallysensitive material such that a difference in the thickness of theoptically sensitive material in different regions overlying theintegrated circuit is substantially defined by a difference in the firstand the second trench depths.
 9. The method of claim 8, wherein theoptically sensitive layer comprises at least one semiconductornanoparticle.